Responce from Marbles reagent etching of weld profile
Responce from Marbles reagent etching of weld profile
(OP)
Hi everybody,
I am no metallurgist but I have a basic understanding of metals.
We have been laser spot welding 304SS and to check out the welds I have been creating profiles of the weld. i.e. I grind down into the centre of the spot weld, polish down and then etch with marbles reagent so I can see the penetration of the weld.
Now, we are matching a previously done weld by a third party, we have our laser welder set to make welds just like the third party. When I create a profile I can see the penetration is spot on... however our welds are still much weaker! Now the only difference I can see on the etched profiles is that the third party weld appears to give a stronger clearer response (i.e. the weld area gives a darker colour after the same immersion time in the marbles reagent)
I understand that the marbles reagent lets me see grain boundaries, so I guess this means the third party weld has more closely packed grains to give the darker colour... how can we replicate this ? do we perhaps need to cool the weld pool down quicker ? heat it faster ? keep it hot for longer ?
Any help would be great, thanks in advance!
I am no metallurgist but I have a basic understanding of metals.
We have been laser spot welding 304SS and to check out the welds I have been creating profiles of the weld. i.e. I grind down into the centre of the spot weld, polish down and then etch with marbles reagent so I can see the penetration of the weld.
Now, we are matching a previously done weld by a third party, we have our laser welder set to make welds just like the third party. When I create a profile I can see the penetration is spot on... however our welds are still much weaker! Now the only difference I can see on the etched profiles is that the third party weld appears to give a stronger clearer response (i.e. the weld area gives a darker colour after the same immersion time in the marbles reagent)
I understand that the marbles reagent lets me see grain boundaries, so I guess this means the third party weld has more closely packed grains to give the darker colour... how can we replicate this ? do we perhaps need to cool the weld pool down quicker ? heat it faster ? keep it hot for longer ?
Any help would be great, thanks in advance!





RE: Responce from Marbles reagent etching of weld profile
Are you and the third party using the same machines with the same set-up for spot welding, or are there significant differences in the machines and the set-ups?
Maui
www.EngineeringMetallurgy.com
RE: Responce from Marbles reagent etching of weld profile
RE: Responce from Marbles reagent etching of weld profile
You can see that ours is much lighter, however a darker shade can be seen within the weld.
Welding machines are very different, this is obviously the major problem, if we can figure out why the weld is darker we can tweak the settings to try and give the same strength.
Thanks for looking.
RE: Responce from Marbles reagent etching of weld profile
Maui
www.EngineeringMetallurgy.com
RE: Responce from Marbles reagent etching of weld profile
I've also had to cut out the weld image as the full image contains propriety information.
RE: Responce from Marbles reagent etching of weld profile
I presume you don't have any access to the 3rd party laser welding procedure otherwise duplication would be straight forward. So, you are attempting to reverse engineer a quality laser weld using your own equipment.
What are your current welding parameters for the laser spot welds, preparation, cleaning, etc.,? Do you have a welding procedure to follow or developed your own? The appearance of the weld does not necessarily equate to strength. Have you tested the weld coupons to determine and compare strength levels?
RE: Responce from Marbles reagent etching of weld profile
I have tested the welds on a tensile machine and the 3rd party welds are at least 50% stronger..
This is a guess, but perhaps the 3rd party welder cooled quicker? some sort of heat sink?
RE: Responce from Marbles reagent etching of weld profile
http://www.uslasercorp.com/envoy/welding.html
Maui
www.EngineeringMetallurgy.com
RE: Responce from Marbles reagent etching of weld profile
RE: Responce from Marbles reagent etching of weld profile
Waterless Kalling's reagent
RE: Responce from Marbles reagent etching of weld profile
mAUI
www.EngineeringMetallurgy.com